Centrifugal compressor



Sept. 2, 1952 m; 2,609 141 CENTRIFUGAL COMPRESSOR Filed Oct. 2, 1945 2SHEETS-SHEET 1 Sept. 2, 1952 G. AUE 2,609,141

CENTRIFUGAL COMPRESSOR Filed Oct. 2, 1945 2 SHEETS-SHEET 2 INVENTORGeafy flue BY Q WAQXMR L Qwm ATTORNEYS Patented Sept. 2, i952 PATENTJOFIFICE goenran uoer COMPRESSOR Georg Aue, Winte1{thur, Switzerland,assignor to Sulzer Frer'es. Societe Anonyme, Winterthur,

Switzerland Application.OctobciiZ. 1945.;SierialNo. 619,774.-."Inifiwit'zerland October 2.19M

'{=locity" into-- a directionat least-approximately parallel 'to' the-rotcir axis and "leading to diffusers having generally'straight axes'-in-=-which' that medi'um is then slowed down. I

In employing the wcrd "axesto describe the central or median lines aboutwhich thediifu'sors are arranged applicantdoes -net intend to limit'such lines to the: rigid geometric straigh-tnessof an axis ofrota-tion, but rather to include lines having sligh-t andaerodynamically.unimportant depar-tures from such straightness. l See,New entury Dictionaryy2-vol; ed, September 1930.

Thediffusors are preferably of, circular" cross- -section. Thechannel'smf the intermediate-mem- 'ber which guide andturn-the'floir'rromrrotor "to diifusors, may at the rotor end be ofapproximately rectangular cross-section and at the diffusor end ofcircular cross section, both with about the samecross-sectional-area. Itis admantageousior these :directing channels, :and the difiusorsconnected to them; to be'contai-ned between an-outer guidecasing and'aninner guide member in the form of a'body of revolution symmetrical withrespect to the'rotor axis. The; axes of the difiusors themselves-may cutthe; rotor axis atanyfinite'point or -at infinity, ior theytmay bearranged oblique to but -not-intersecting it.

ln fthe conversion ct -energy "in a centrifugal blower theefficiencyofthe diffuser plays; an ,important part; since; as "is known; only about.one- "half to three-quarters of "the delivery pressureis produced upto-the-outl-et of the rotor, whilst the r exis in the-issuing deliveredmedium in the form of .kinetic energy and has to be converted ,astar a'spossible into pressurelin the diffusor.

fillll'hepest efficiency of lallifdesigns ofedifiusorsispossessedby'thosewhich consist of a comically expanding pipe ofcircular cross-section having a. straight axis. In radial compressors itis old to divide the air-stream issuing from the rotor into separatestreams by means of a suitably subdivided guide spiral and to turn thesestreams from that spiral into straight-axis difl'usorsg ly ing in planesat right angles to the rotor axis. These streams are slowed down inthediflusors and thus obtain pressure, the retarded stream issuing, ifrequired, into ;a bladelcss-spiral casing,

Whereafter further turning iiiplanes 'at -ri'gh't angles "to the rotoraxis, it is led to the outlet branches. Such-spirals with straight-axisdiffusors-have large diameters and therefore take up, much spaceradially, so that,-apart-fromthe drawback ofincreasing-the weight" andthe great cost of manufacturing such --a 1 spiral, it is ;jdifficulttofit such a-compressor intoa piantzasan auxiliary machine. Inaddition;suchknown outletspirals equipped with diffusers can' only -beadopted for centrifugal machines With-radialilow of the medium handled.An obvious means-of reducingjthe diameter ofthe spiralcasin is toconstruct thediffusor with the axis bent. iiBut then additional Coriolisand -,centrifugal*fo1 ces make their appearance in the medium handled,causing the flow of the medium ;to be deflected {from the guiding Wallsand thus giving always aworse diffusorefficiency than-withstraight-linediifusors. :Also diffusorswith cross- 'jectedto' thebraking action of the walls ontwo sides. The alternative drawbacks ofcomparatively' large casing diameters ordiffusoli with a poor. degreevof efficiency can both be; avoided by the present invention.

Embodiments of theinvention are illustrated by. Way-0f example intheaccompanying drawing, in which:

"Fig. 1 shows an axial cross-section,ofla cen- Itrifugal compressor;'Figs..2,3. and 4 show sections onthe planes I-,-I II-"-II. and III-+IIIof Fig. 1;

Fig. 5.shows an end view of. the compressorin part section on the planes1-11 and.II-..II. of Fi 1; and

'fFi sinclusive,.reprersentldifierentforms oiarransement oithedifiusors. g The sh ft l of the. rotor ;.2;is... .arried @in.-.;thebea'rings"3 ana t. The-bearings 'is-arrangediin thewinlfit c n paniline. bearing .4. in .the

,guidemember 5. At theinlet efidhth'egshafi I axis a: in order toprevent bending stresses being caused by centrifugal forces. In order toobtain a high-stage-pressure ratio the rotor 2 can be driven at acorrespondingly high velocity, which may in certain circumstances begreater than the velocity of sound in the medium handled, for instanceat 330 metres per sec. and more, without the absolute outlet velocity ofthe medium delivered by the rotor 2 exceeding or reaching this velocityof sound, the tapering screw-line of the blades 8 being arranged in thedirection of rotation opposite to that of the rotor and thus ensuring anoutlet angle on the rotor 2 in accordance with this requirement.

The guide member 6, formed as a solid of revolution symmetrical withrespect to the rotor axis x, is arranged at the outlet end of the rotor2. Both the rotor 2 and the guide member 6 are surrounded by the casing9, which is connected at the inlet end to the inlet casing part bysupporting ribs l0, and to the guide member 6 by the partition walls II.The intermediate piece lying between the cross-sectional planes I1 andIIII is provided with directing channels I2, which are formed by thecasing 9, the guide member 6 and the partition walls II. It would bepossible in the intermediate piece to form the partition walls of thechannels as blade grids,

which particularly for rotors with slow specific speed, whose streamissuing from the rotor requires to be greatly deviated, could be formedas split wings. The channels l2 are bent from a direction parallel tothe rotor blades to a direction parallel to the difiusor axes Y in sucha way that the medium flowing out from the rotor in a direction obliqueto the rotor axis, is deviated into a direction at least approximatelyparallel to the rotor axis. At the inlet side of the intermediate piece,the channels I2 are of rectangular crosssection as shown in Fig. 2, thepartition walls being then thin and offering only slight resistance tothe medium flowing in. The cross-section of the channels l2 changes itsshape continually along the axis of flow through the intermediate piecein order to form on reaching the transverse plane IIII, shown in Figs. 3and 5, a circular cross-section of about the same area as therectangular entry cross-section (I-I).

By doing without a difiusor effect in this intermediate piece, the flowis prevented as much as possible from leaving the guiding Walls.Approximately from the section IIII downwards, the channels l2 lead intodiffusers l3, which are for the most part straight and contained betweencasing 9 and guide member 6, the circular cross-sections graduallywidening, so that the conversion from velocity energy into pressureenergy takes place under the most favourable conditions. The axes y ofthe diifusors [3 may then cut the axis :r of the rotor at infinity or ata finite point or may be arranged oblique to but not intersecting it, asshown in Figs. 6-8. From the diffusors l3 the medium handled arrivesapproximately free from twist and with components of velocity mostlyparallel to the axis into the angular space 14 between the guide casing9 and the guide member 6 and leaves it through the pipe l5 leading tothe point of use.

Instead of the channels l2 and the diffusors l3 being formed as hollowspaces in a cast piece as .4 in the embodiment illustrated in Figs. 1-5,they could, without departing from the invention, also be made of sheetmetal and so supported with respect to each other that the desiredmutual position is ensured. In this way it would be possible to reducethe weight of the compressor considerably. i

It would also be possible for the axes of all diifusors to be parallelto each other, but nevertheless slightly inclined to the rotor axis.Likewise the point of intersection of the diflusor axes might lieoutside the rotor axis.

I claim:

1. A centrifugal compressor assembly for producing a high stage pressureratio, including in combination an approximately conical rotor arrangedto discharge at its bigger end, a, plurality of stationary diffusorsarranged around the rotor axis with their inlet ends toward the rotordischarge end but axially displaced therefrom, said diffusors havingcircular cross-sections and generally straight axes the directions ofthese axes deviating by less than 20 from the direction of the rotoraxis, and a stationary intermediate portion between the rotor dischargeend and the difiusor inlet ends provided with directing channels,matching, as to cross-section and direction, at the one end with thediffusor inlet ends and. having curved axes and along these curved axescross-sections of substantially constant area but continually variableshape, to match, as to crosssection and direction, at the other end withthe discharge from said rotor.

2. A centrifugal compressor assembly as claimed in claim 1, thedirecting channels and the diffusors of which are contained between a.guide casing and a guide member, said member forming a solid ofrevolution symmetrical to the rotor axis.

3. A centrifugal compressor assembly as claimed in claim 1, the axes ofwhose difiusors intersect the rotor axis at a finite point.

4. A centrifugal compressor assembly as claimed in claim 1, the axes ofwhose difiusors intersect the rotor axis at infinity.

5. A centrifugal compressor assembly as claimed in claim 1, the axes ofwhose diffusors being arranged oblique to the rotor axis but notintersecting it.

GEORG AUE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 521,962 McConnell et a1. June 26,1894 1,042,506 De Vallat Oct. 29, 1912 1,430,141 Angus Sept. 26, 19221,771,939 Rees July 29, 1930 1,785,354 Lawaczeck Dec. 16, 1930 1,932,231Schmidt Oct. 24, 1933 1,959,703 Bermann May 22, 1934 2,463,976Kilchenmann Mar. 8, 1949 FOREIGN PATENTS Number Country Date 274,224Italy 1930 409,450 Germany Feb. 6, 1925

